added an initial unionfs lib

lib/unionfs.lua

@@ -0,0 +1,106 @@
+local unionfs = {}
+
+local function normalise(path)
+ return table.concat(fs.segments(path),"/")
+end
+
+function unionfs.create(...)
+ local paths,fids,fc = {...}, {}, 0
+ for k,v in pairs(paths) do
+  paths[k] = "/"..normalise(v)
+ end
+ local proxy = {}
+ local function realpath(path)
+  path = path or ""
+  for k,v in pairs(paths) do
+   if fs.exists(v.."/"..path) then
+    return v.."/"..path
+   end
+  end
+  return paths[1].."/"..path
+ end
+ 
+ function proxy.spaceUsed()
+  return fs.spaceUsed(paths[1])
+ end
+ function proxy.spaceTotal()
+  return fs.spaceTotal(paths[1])
+ end
+ function proxy.isReadOnly()
+  return fs.isReadOnly(paths[1])
+ end
+ function proxy.isDirectory(path)
+  return fs.isDirectory(realpath(path))
+ end
+ function proxy.lastModified(path)
+  return fs.lastModified(realpath(path))
+ end
+
+ function proxy.exists(path)
+  return fs.exists(realpath(path))
+ end
+ function proxy.remove(path)
+  return fs.remove(realpath(path))
+ end
+ function proxy.size(path)
+  return fs.size(realpath(path))
+ end
+
+ function proxy.list(path)
+  local nt,rt = {},{}
+  if #fs.segments(path) < 1 then
+   for k,v in pairs(paths) do
+    print(v.."/"..path)
+    for l,m in ipairs(fs.list(v.."/"..path)) do
+     nt[m] = true
+    end
+   end
+   for k,v in pairs(nt) do
+    rt[#rt+1] = k
+   end
+   table.sort(rt)
+   return rt
+  else
+   return fs.list(realpath(path))
+  end
+ end
+
+ function proxy.open(path,mode)
+  local fh, r = fs.open(realpath(path),mode)
+  if not fh then return fh, r end
+  fids[fc] = fh
+  fc = fc + 1
+  return fc - 1
+ end
+
+ function proxy.close(fid)
+  if not fids[fid] then
+   return false, "file not open"
+  end
+  local rfh = fids[fid]
+  fids[fid] = nil
+  return rfh:close()
+ end
+ function proxy.write(fid,d)
+  if not fids[fid] then
+   return false, "file not open"
+  end
+  return fids[fid]:write(d)
+ end
+ function proxy.read(fid,d)
+  if not fids[fid] then
+   return false, "file not open"
+  end
+  return fids[fid]:read(d)
+ end
+ function proxy.seek(fid,d)
+  if not fids[fid] then
+   return false, "file not open"
+  end
+  return fids[fid]:seek(d)
+ end
+
+ return proxy
+end
+
+return unionfs